fix: Adapt assistant sdk to hlp

[MichalAI21]

• Add schemas to create/modify plan.
• In plan creation/modify: code arg can be a callable, schema can be a class

[Josephasafg]

Great! Can you please move this inline to the call? something like -

return remove_not_given(
            {
                "code": code,
                "code": code_str,
                "schemas": [self._parse_schema(schema) for schema in schemas] if schemas is not NOT_GIVEN else NOT_GIVEN,
                **kwargs,
            }
        )

[Josephasafg]

If you pass None here the message would be
Code can't be parsed: None
That's a strange behavior for the user.

Perhaps something like this -

class CodeParsingError(AI21Error):    
    def __init__(self, details: Optional[str] = None, message: Optional[str] = None):
        self.message = message or f"Failed to parse code: {details or 'No details provided'}"
        super().__init__(self.message)